This invention relates to a combination of a hollow member and a backing member which is inserted in the hollow member to function as a nut upon securement of another member to the hollow member as well as to reinforce the portion of the hollow member where such other member is secured. More specifically, this invention relates to a combination of a hollow member and a backing member in which the backing member may be accurately positioned in the hollow member without necessity of access to the interior of the hollow member.
When it is necessary to mount some members, such as hinges, to hollow members of various shapes by machine screws, such steps have been employed as inserting in a hollow member a flat backing member having female screw thread holes and functioning as nuts and passing screws from the side of a hinge so as to tighten it against the backing plate. When it is impossible to give access to the interior of a hollow member due to its shape and size, a mounting jig having a recess for accommodating a backing plate is used for conveying the backing plate from the outside of the hollow member to the place in the hollow member where the backing plate aligns with holes formed in the hollow member for passing screws. After this operation, the screws are tightened against the backing plate for supporting the same. This assembling operation is very burdensome and time consuming.
Japanese Utility Model Publication No. 25567/1979 shows an idea which improves the abovementioned assembling operation. According to this Publication, one end of a backing member, which is to be inserted in a hollow member and has female screw thread holes, is extended to an open end of the hollow member where a registration shoulder is formed. By engagement between this shoulder and the edge of the open end of the hollow member, the backing plate is placed in a desired position. However, with this technique, various kinds of backing plates are necessary according to the distance between the edge of an open end of a hollow member and screw passage holes in the hollow member. This is a drawback in the light of management of parts and production cost. Furthermore, it is impossible to use a plurality of backing plates in one hollow member. This is another drawback since the application of the technique should be limited.